When Adam chose to sin he exalted himself as God, to know good and evil (Ge 3:22); that is, Adam started deciding for himself what good and evil are, rather than letting God define it. He expressed this by deciding to disobey God, to sin, to break God’s Law. (1Jn 3:4)
In doing this, Adam effectively removed God from the center of his own world view and placed himself in the center, as if he were God. The basic problem with this is that Adam never was, nor ever could be the actual center of any coherent world view: the center of our universe must also be imposed on everyone else as the center of their universe: this is the definition of center.
So, Adam effectively chose to orient himself around a lie, and this corrupted and distorted his every impulse, emotion and thought pattern from that moment forward; it blinded him to cosmic reality and caused him to live in delusion, a type of spiritual death.
Everyone has a world view, something about which they orient their behavior, a center to align their thoughts and actions into a coherent, meaningful focus. This center is either God or it isn’t; if we try to displace Him we’re making the same mistake Adam did, with the same consequences.
The way we do this, take God out of the center of our world view and place ourselves there, is by defying God. We defy God by breaking His law on purpose, rebelling against His revealed will. We first conclude God isn’t good, that His laws aren’t good, and that if we disobey we’ll be in a better place. Sin always works this way, every time.
Consider the first sin: Satan first drew attention to God’s command, “Yea, hath God said?” (Ge 3:1) When he claimed God was evil (Ge 3:4-5) and made sin look good (6), we all went for it. (1Co 15:22)
It doesn’t really matter which law we break; for Adam it was a dietary restriction: “Thou shalt not eat of it.” (Ge 2:17) There is then a very real and practical sense in which every willful sin is equivalent: it’s both an expression of defiance against God and an attack on His holy character, claiming God isn’t good and can’t be trusted.
Breaking God’s law not only offends and angers God personally, it grieves Him because it misaligns us with reality in a fundamental way: God actually is the center of the universe, nothing else could ever be, and when we choose another center it causes misalignment within us on every level of existence. Like an off-center, out-of-balance wheel that wobbles out of control when put to work, sin results in a dysfunctional, pervasive corruption of the mind and spirit.
So, if God tells us to do something, or not to do something, is this sufficient reason to obey? If it depends, or if we’re any more inclined to obey when we think it will be good for us, we’re still disrespecting and distrusting Him, pushing God out of the center of our universe and placing ourselves there. There is no fear of God in the soul that willfully defies Him, no true knowledge (Pr 1:7) or wisdom. (Pr 9:10) This is the way of death.
This is where we all start out: in Adam, going our own way right along with him. When God mercifully intervenes, giving us repentance and rescuing us, then knowing His will is enough, moving us to obey from the heart.